Re: More info: 2.1.108 page cache performance on low memory

Rik van Riel
1998-07-23T21:33:04Z

On 23 Jul 1998, Zlatko Calusic wrote:

> One wrong way of fixing it is to limit page cache size, IMNSHO.
>
> I tried the other way, to age page cache harder, and it looks like it
> works very well. Patch is simple, so simple that I can't understand
> nobody suggested (something like) it yet.

These solutions are somewhat the same, but your one may take
a little less computational power and has a tradeoff in the
fact that it is very inflexible.

> --- filemap.c.virgin Tue Jul 21 18:41:30 1998
> +++ filemap.c Thu Jul 23 12:14:43 1998
> + age_page(page);
> + age_page(page);
> age_page(page);
> If I put only two age_page()s, there's still too much swapping for my
> taste.
> With three age_page()s, read performance is as expected, and still we
> manage memory more efficiently than without page aging.

This only proves that three age_page()s are a good number
for _your_ computer and your workload.

> Comments?

As Stephen put it so nicely when I (in a bad mood) proposed
another artificial limit:
" O no, another arbitrary limit in the kernel! "

And another one of Stephen's wisdoms (heavily paraphrased!):
" Good solutions are dynamic and/or self-tuning "
[Sorry Stephen, this was VERY heavily paraphrased :)]

Rik.
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